Combined clarifier and flocculating apparatus



April 1941- v H. A. LINCH. 2.238.024

COMBJNED CLARIFIER AND FLOCCULATING APPARATUS Filed July 30, 1938 3 Sheets-Sheet 1 F l G l 1 l4- IO III E 1,

BY HARRY A.L|NCH- ATTORNEY.

H. A. LINCLH April 8, 1941.

consmnn CLARIFIER, AND FLOCCULATING APPARATUS s Sheets-Sheet 2 Filed July 30, 1938 FIG INVENTOR. HARRY A,LINCH ATTORNEY.

April 1- -H. A. LINCH 2.238.024

COMBINED CLARIFIER AND FLOCCULAIING APPARATUS Filed July 50, 1938 3 Sheets-Sheet 3 F'IG.'6.

FIG.7.

a F|s.a.

INVENTOR.

HARRY A; LINCH ATTORNEY.

llllarry i l. lllimclh, maroucclr, hi... "lit, ausigncr to The molar @ompany, c., ltleur '"iforlt, "it, a corporation oi llelatrare Application .ll'uiy 3t, lfltt, tori-all l lo, il tlbliil'l (til. tiltilt) t llilaims.

This invention relates to the treatment of turbid liquids that have solid impurities therein, tor the purpose of clarifying such liquids. Such liquids are exemplified by impure Water, sewage,

trade wastes and the like.

Such liquids require treatment in a substantially continuous manner and some of the impurities thereof being colloid-like, require some type oi treatment such as flocculation to render the suspended solids settleable. The solids settle continuously in theform of sediment,and in order to have the treatment plant operate continuously, it is desirable to have this sediment continually removed or discharged from its place of deposition.

Accordingly, this invention revolves about a liquid-treatment plant that has as essential components thereof a flocculation zone and a mechanically-cleaned sedimentation zone.

Fiocculation may be defined herein as the coagmenting and. amassing of suspended solids into integrated flocs and the conditioning of those fiocs into settleability by the methods exemplified.

, by the use of bladed paddle assemblies moving in repetitive paths for setting up in the liquid currents suflicient for causing coalescing collisions between the suspended solids strong enough to bring about a multiplicity of such collisions, but

gentle enough not to tear apart the fragile coalesced or integrated flocs resulting from those collisions. The currents are also of a type that tend (1) to sweep settled flocs back into suspension for further integration thereof, and (2) to condition or condense the thus-formed flocs to improve their settleability. Thus the floccula-.

tion zone is characterized by agitation, whereas the s'edimentationzone is characterized by quiescence; therefore we have in these two zones opposing conditions so that the condition of one must not overcome the condition in the other.

: And yet it'becomes quite important to transfer the flocculatedliquid from the flocculation zone to the quiescent sedimentation zone under conditions whereby the 11005 are drifted from one to ,tial damage thereto and without substantial interference between the flocculating agitation and the quiescence of the sedimentation.

to as Dorr clarifiers or thiclreners.

li/lechanically-cleaned sedimentation tanirs or settlers have been lrnovvn for many years. They have tended to take embodiment in a, round tank in which the siudge impelling or waking mechanism slowly travels and sweeps over the bottom. of the tanlr to bring about the discharge of the sludge or sediment therefrom without upsetting the condition of quiescence requisite for sedimentation. Such tanlrs, having raking blades rotating about a vertical axis, are frequently referred But when it comes to close juxtaposition of a flocculation zone and settler of this general type, difliculties are encountered, because efficient flocculation zones are usually rectangular in shape and it is not easy to combine a, rectangular flocculation zone with a round clarifler. Therefore, another feature of this invention is the combining of a rectangular flocculation zone with a substantially square clarifler, while providing the sludge-raking arms that rotate about a central vertical axis with corner-exploring blades that automatically enter the corners of the square tank to rake sediment therefrom into the path of the blades that are rotating over and sweeping a circular area in the clarifler. This combination has many advantages in that it is cheaper to build, takes less ground space and is highly eflicient in the ultimate clarifying of the liquid being treated, because it permits of efficient flocculation and efficient drifting of flocculated liquid to the settler. Also, it gives a maximum of settling area with a minimum of raking mechanism.

In designing a flocculation. zone to conform generally to the outline of a rectangular settler, because the liquid to be flocculated must be detained in the flocculation zone for a definite detention period, problems are presented in getting the flocculation zone large enough and in preventing short-circuiting or lay-passing of the liquid in incomplete flocculated condition. So another feature of this invention resides in the preventing of this short-circuiting by providing a tortuous flowpath for the liquid passing through the flocculation zone.

The above-described arrangement requires a cross-flow through the settler, that is, feed entering at one end or side and eflluent beingtaken off at the opposite one. Under such circumstances there is a tendency for the feed to shortcircuit directly to the ovefilow.- To that end, this invention proposes the use of the final series of flocculating blades for also distributing or dispersing feed in the settler to discourage shortcircuiting. I

With these objectives, the invention may be said to comprise a tank or basin, in one end section of which is a flocculation zone employing paddle assemblies operating in repetitive paths for treating the flowing-through liquid to cause suspended solids thereof to become integrated flocs conditioned for settleability, whereupon the conditioned flocs are driitingly flowed from the flocculation zone to the sedimentation zone that is in an opposite end section of the rectangular basin. Further features reside in the tortuous flowpath through the flocculation zone for the purpose of assuring better distribution of the flocculated liquid to the settler; the particular paddle arrangement shown in the flocculation zone, where some of the paddles are disposed parallel to the liquid flow and some transverse thereto; and in having some sections of the liquid flowpath wider than others.

With these and other objects in view, the invention consists in the construction and novel combination and arrangement oi parts hereinafter fully described, illustrated in the accompanying drawings, and set forth in the claims hereto appended, it being understood that various changes in the form, proportion and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit of the invention or sacrificing any of the advantages thereof.

Fig. 1 is a plan view of one embodiment of the flocculation sedimentationunit, with corner-exploring rotary sludge raking arms, and a flocculating zone comprising a plurality of paddle agitated flow sections.

Fig. 2 is a longitudinal section along the line 2-2 of Fig. 1.

Fig. 3 is a section through the flocculation zone along the line 3-3 of Fig. 1.

Fig. 4 is a detail plan view of the outer end portion of a rotary rake arm in the sedimentation zone of the unit, equipped with corner-explorin device.

Fig. 5 is a side view of mechanism shown in Fig. 4.

Fig. 6 is a plan view similar to the one oi! Fig. 1, with the exception that the flocculation zone is modified.

Fig. 7 shows in plan view a modified paddle arrangement in the flocculation zone of a treatment unit according to this invention.

Fig. 8 is a cross-section taken along the line l--8 of Fig. 7.

In the embodiment of the invention, chosen for the purposes of illustration, and shown in the accompanying drawings, l indicates the rectangular tank or basin designed for the clarification of turbid liquids. The tank is subdivided into a flocculation zone II, and a clarification or sedimentation zone II, the zone I2 being defined by side-walls l3, ll, l and I6, and a bottom H. The flocculation zone H is provided with a feed inlet l8 and an outlet I! for flocculated liquid to drift into the sedimentation zone or settler H, the outlet [9 thus constituting influent means for the settler l2. The liquid flowing through the flocculation zone is caused to traverse a tortuous flowpath in which its direction is changed. Such a path in the embodiment shown in Figures 1 to 3. is formed by means of a baille wall 20 forming one section 2| and another section 12 oi the flowpath by way of the end of baiiie wall 20 through an opening 23. In this arrangcmentthe flop/path section or channel section 2! is wider than fiowpath section or channel section 2?.

The flocculation zone i i, and more particularly the wider section thereof M, is provided with paddle assemblies 24 adapted to be rotated in repetitive paths by any suitable prime mover; The purpose of these paddle assemblies 24 is to set up in the liquid to be fiocculated, currents that have a number of functions,(1) they must bring about a multitude of collisions between suspended particles of turbidity that are gentle enough to cause the particles to coalesce or coagment or amass into flocs of appreciable size, with the collisions being strong enough to bring this about, but gentle enough not to disrupt or disintegrate fragile flocs once they are formed; (2) to sweep back into suspension and circulation flocs that have become large enough to settle, so that these already-formed flocs can be used as nuclei to which smaller flocs or particles of turbidity may adhere, whereby flocs of increased size are those built up or integrated; and (3) to give such rolling motion to the integrated flocs that they are condensed or conditioned into settleability. These currents are set up by the use of paddles such as are illustrated, especially when such paddles rotate in the same direction, whereby the direction of rotation is such that the paddies, when above their axis of rotation, tend to impel liquid before them away from the feed l8; whereas, the paddles below their axis of rotation tend to impel flocs that have a tendency to settle, or have settled, toward the feed N. This action can be facilitated by the use of curtain walls or baflles 25, more clearly indicated in Fig. 3, around the end of which liquid flows.

Assuming now that the liquid which continually passes through the opening 23 is substantially flocculated, the problem is presented of passing it into the settler I! in a manner that (1) it is integrated and conditioned flocs are not disrupted, and (2) that they are kept in suspension and prevented from settling; and (3) distributed fairly thoroughly to the settler I! so that there is no tendency either toward concentration thereoi in the feed to the settler through the opening I,

or at a speed that would interfere with the quiescence of the liquid in the settler. Short-circuiting or by-passing is also thus discouraged. This can be accomplished in one way by having the flocculation section or channel section 22 narrower than the main flocculation section or channel section 2|, so that the flow-through oi the liquid is slightly increased in speed, and the providing therein of a lesser number of paddle assemblies a for keeping the flocs in suspension, although other means for accomplishing this purpose are shown in modified embodiments later to be described herein.

In order to control the passage or drift of the flocculatad liquid from the narrower section 22, there is provided means for varying the depth of the opening I! or constricting parts of this opening above the top of the wall ll. These can be planks or other adjustable means, because if the flocculated liquid is caused to flow over a weir, and the weir is not sufliciently submerged, the weir has a tendency to break up the flocs. Therefore the flocculated liquid is being drifted and thoroughly dispersed to the settler l2, having had the particles of turbidity of the liquid flrst integrated into flocs and then conditioned ior settleability, but kept in suspension until the sedimentation zone is reached. The channel sec ions it and 22 are disposed generally at t angles to the general flow path of liquid 1 through the settler escapee in the settler it there is provided an upstanding pier dd contributing to the support of a cage-drum or other structure 3i, adapted to encircle or surround the pier, and that is rotatable by any suitable prime mover M, preferably also deriving its support from the pier 30. The cage it carries rake arms 32, preferably in balanced relationship, which arms rotate as a unit with the cage ti. ried by the rake arms 32 in the relationship that when the cage M is rotated with its rake arms and blades, the blades sweep over the bottom of the tank in a circular path and impel sediment settled to the bottom of the tank as sludge and made up of solids that were in suspension in the liquid, to a sludge-discharge cone or sump it, from which they can be removed by a discharge conduit or other discharge means. On the side walls of the tank is provided an effluent launder it, into which clarified liquid flows to discharge through a clarified-liquid conduit or discharge d'l. Thus, as liquid enters the clari- .tier or settler it along the side it, there is a general liquid flow path thereacross. Sediment that settles in the corners 38 of the tank is raked into the circular path of the rotating or traveling rake arms 32, by means of corner-exploring blades it, supported from, and carried by, the ralre arms it by means of a double-link construction it and ti. The link dll is pivoted to the rake arm at M, and the link M is pivoted to the rake arm at M, the arm ll having an adjustable counter-balance M. The rake arm ilt in the embodiment shown herein is acted'upon by'a spring or springs 45 tied to the rake arm by some suitable connection 46, the spring acting always to cause extension of the cornerexplorer 39, whereas the corner-explorer is pushed out of extended position against the spring tension as its end engages with the wall of the settler. Retracted position is shown in full lines in Figure l, and extended or cornerexploring position is shown in dotted lines. In operation the liquid to be flocculated is continually ied to the inlet Hi. It may be previously 33 represents raking blades cari overflows into the effluent launder 3t, and from thence out of the tank through the conduit 31; so here we have an efficient apparatus, rectangular in form, for first flocculating the turbid liquid and settling therefrom settled solids in the form of sludge with the sludge passing from the liquid by one path, and the clarified liquid passing from the apparatus by another path.

* zone dB, in which a baffle wall 50 is disposed at dosed with some coagulating chemical as is usual flocculation zone, the liquid is drifted with its does still in suspension, to, and dispersed in, the settler or sedimentation zone l2, under conditions where the agitation of the flocculation zone does not extend to, or interfere with, the quiescence necessary in the sedimentation zone. The liquid in the sedimentation zone or settler it, being held in quiescence, permits the floos and other solids in suspension to settle to the floor of the settler in theform of sediment, which is usually called "sludge? Rotation of the rake arms 32, slow enough not to interfere with quiescence, causes the sediment to be impolled to the sludge discharge. Sediment falling in the corners of the square settler is raked therefrom into the circular path of the rake arms 32 and rakes 33, so that the entire bottom of the tank, including the corners, is continually swept substantially clean of sludge, whereby no .sludge is left in the tank long enough to become septic, the liquid from which solids and turbidity having thus been removed, continually of flocculated material a slope with respect to the confining walls of the flocculation zone. This creates a first-flow section iii of gradually diminishing width, provided with a series of paddle assemblies 52 to 51,

alternating with transverse baflle walls or partial partitions 58 to lit which" function with respect to the paddle assemblies substantially in the manner described in connection with the battle walls iii of Figs. 1 and 3. From the firstflow section, and passing around the end of the sloping bafi'le wall it, the flowing and flocculating liquid then reverses its flow direction as it enters. into a corresponding secondflow section tilt in which no paddles are provided, and which tapersdown with regard to eifective flow section somewhat in proportion to the diminishing flow volume that drifts off laterally along the width of the tank and into the sedimentation zone it in the manner indicated by arrows t l. Thus the flow section 63 serves in effect as a flow transfer section between the first-flow section 62 and the sedimentation zone it. An inlet for the flocculation zone 48 is indicated at 65.

Figs. 7 and 8 show a somewhat modified arrangement of paddle assemblies in the flocculation zone; again there are shown a first relatively wider flow section 66 and a second relatively narrower flow section 61, established within the flocculation zone by means of a bafile wall 68. Paddle assemblies 69 to 15 in this case have paddle shafts 69a to 15a which extend through the baffle wall 68 so that the free end portions 6% to 15b of these shafts may carry paddle elements such as indicated by the numerals 16 to 84, preventing the sedimentation in this flow section. I claim: 1. A liquid clarification apparatus comprising a tank structure having a sedimentation section of substantially rectangular settling area adapted for holding in quiescence liquid having solids in suspension long enough for solids to settle and form sediment in the tank, motivated mechanism for removing sediment fromthe tank, outflow means for removing clarified efiiuent from an end portion of the sedimentation section, means for supplying the opposite end portion of the sedimentation section with flocculated liquid, whereby the liquid flows through the sedimentation section in one general direction, which supply means comprises at least two channel sections adapted for liquid flow therethrough, one of which channel sections is wider than the other, and the length of which channel sections extends substantially at right angles to said general direction of flow, a partial partition acting as a common wall between said channel sections and around one end of which partition liquid after having flowed through the wider channel section may pass therefrom to the narrower channel section, said narrower channel section having means to provide infiuent passage along its length for liquid in substantially uniform distribution into said sedimenta- 2. Apparatus according to claim 1, with the addition of means sufiiciently agitative to prevent the settling of solids in the narrower channel section.

3. Apparatus according to claim 1, in which the partial partition is disposed at an angle with respect to the Walls of the tank structure, so as to gradually diminish the flow cross-section of the wider channel section, as Well as of the nartion section whereby the liquid flow is distributed 10 rower channel section.

substantially uniformly over the width of the settling area.

HARRY A. LINCH. 

